In this article

How do I change cookie settings?

Firefox will display a lock icon with red strike-through in the address bar when a login page you’re viewing does not have a secure connection.
This is to inform you that if you enter your password, it could be stolen by eavesdroppers and attackers.

Note:

Cookies are enabled by default in Firefox.

Click the menu button and choose Options.Preferences.

Select the Privacy & Security panel and go to the
Cookies and Site Data section.

Select Accept cookies and site data to enable cookies. To
disable cookies,
select Block cookies and site data and use the drop-down
menu next to Type blocked to choose the type of cookies to block.

Keep until:They expire: Each cookie will be
removed when it
reaches its expiration date, which is set by the site that sent the
cookie.Firefox is closed: The cookies that are
stored on your
computer will be removed when Firefox is closed.

Close the about:preferences page. Any changes you've made
will automatically be saved.